Re: Color difference equations [was: Color Measurement]
Re: Color difference equations [was: Color Measurement]
- Subject: Re: Color difference equations [was: Color Measurement]
- From: Marc Levine <email@hidden>
- Date: Thu, 16 Jul 2009 18:26:53 -0400
Hi all,
Personally, I think that questions regarding dE formulas come up
because it is unclear how to categorize variance. On one side, you
have the variation built into the hard technology used to quantify and
reproduce color: measurement devices, inks, papers. My opinion is that
these things should be "scored" by non-eliptical formula: dE76. My
reasoning is that the variation of a device should not be scaled
against me. Variation of the device should be measured as an
independent property. Some may say "but you'll never see that in the
yellow". To me, that doesn't matter. Variation is a measure of
accuracy and repeatability. It should have nothing to do with me. Of
course, I'm no color scientist.
I believe eliptical formulas should be used to grade color visual
color matching quality. So....when I get a print our of a RIP and
evaluate the IT874 lab values against the target char-dat, then
yes...it makes a lot of sense there. Now the only problem is picking
which elliptical formula works best for you. I have measured many a
sample where dE94 bests dE2000 in lowest dE. Unfortunately, this will
likely always be a problem as "color as it appears" is fundamentally
subjective and different users may see different benefits with
different formulas. You can use whatever formula you want the score
anything...and that's better than nothing at all. That being said, I
believe that the application actually dictates which formula you
SHOULD use...at least regarding elliptical (76) vs. non-elliptical
(2000 and counting...)
My 2 pence.
Marc
--
Marc Levine
Color Management Grouper. Mmmmm.......Grouper.......
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